Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions
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Authors
Vesna, O.
Sjögren, Staffan
Samburova, Vera
Kalberer, Markus
Gäggeler, Heinz W.
Ammann, Markus
Author (Corporation)
Publication date
18.08.2008
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Type
01A - Journal article
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Parent work
Atmospheric Chemistry and Physics
Special issue
DOI of the original publication
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Series
Series number
Volume
8
Issue / Number
16
Pages / Duration
4683-4690
Patent number
Publisher / Publishing institution
Copernicus
Place of publication / Event location
Göttingen
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Abstract
Unsaturated fatty acids are important constituents of the organic fraction of atmospheric aerosols originating from biogenic or combustion sources. Oxidative processing of these may change their interaction with water and thus affect their effect on climate. The ozonolysis of oleic and arachidonic acid aerosol particles was studied under humid conditions in a flow reactor at ozone exposures close to atmospheric levels, at concentrations between 0.5 and 2 ppm. While oleic acid is a widely used proxy for such studies, arachidonic acid represents polyunsaturated fatty acids, which may decompose into hygroscopic products. The hygroscopic (diameter) growth factor at 93% relative humidity (RH) of the oxidized arachidonic particles increased up to 1.09 with increasing RH during the ozonolysis. In contrast, the growth factor of oleic acid was very low (1.03 at 93% RH) and was almost invariant to the ozonolysis conditions, so that oleic acid is not a good model to observe oxidation induced changes of hygroscopicity under atmospheric conditions. We show for arachidonic acid particles that the hygroscopic changes induced by humidity during ozonolysis are accompanied by about a doubling of the ratio of carboxylic acid protons to aliphatic protons. We suggest that, under humid conditions, the reaction of water with the Criegee intermediates might open a pathway for the formation of smaller acids that lead to more significant changes in hygroscopicity. Thus the effect of water to provide a competing pathway during ozonolysis observed in this study should be motivation to include water, which is ubiquitously present in and around atmospheric particles, in future studies related to aerosol particle aging.
Keywords
Subject (DDC)
550 - Geowissenschaften
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ISBN
ISSN
1680-7324
1680-7316
1680-7316
Language
English
Created during FHNW affiliation
No
Strategic action fields FHNW
Publication status
Published
Review
Peer review of the complete publication
Open access category
Gold
License
Citation
VESNA, O., Staffan SJÖGREN, Ernest WEINGARTNER, Vera SAMBUROVA, Markus KALBERER, Heinz W. GÄGGELER und Markus AMMANN, 2008. Changes of fatty acid aerosol hygroscopicity induced by ozonolysis under humid conditions. Atmospheric Chemistry and Physics. 18 August 2008. Bd. 8, Nr. 16, S. 4683–4690. DOI 10.5194/acp-8-4683-2008. Verfügbar unter: https://doi.org/10.26041/fhnw-9732